Providers of telecommunication services must provide means by which law enforcement agencies can carry out lawful interception and monitoring of telecommunication traffic. For example, the Communications Assistance for Law Enforcement Act (CALEA) of the Federal Communication Commission in the United States of America defines carrier and equipment manufacturer responsibilities for enabling legally authorized surveillance of target communications. Although not yet implemented in ATM systems, packet technologies are covered by the CALEA.
In ATM networks, lawful interception of a communication can be established by establishing a tap at an interception node through which the connection passes between the source node and the destination node. A tap connection is established between the tap and a monitoring station. Within the interception node, the tap copies any communications over the connection, and transmits the copied communications to the monitoring point over the tap connection. The tap is most easily established manually along a Permanent Virtual Circuit (PVC). Since the connection being monitored is a PVC and the route of the connection between the source node and the destination node is known, the choice of which node is to be the interception node is straightforward. A tap connection can then be established manually as a PVC between the interception node and the monitoring station. Such a tap connection is a statically configured connection, and behaves similarly to a point-to-multi-point PVC.
Unfortunately, if the main PVC fails or is moved, the tap must be re-established manually even if the connection follows the same route. This is because the PVC is defined by the ingress and egress endpoints on the interception node, and the PVC may use different endpoints once it is re-established. Additionally, the manual establishment of the tap and of the tap connection is tedious. An automated method of establishing taps would allow faster and more flexible establishment of taps for the purposes of lawful interception of communications within an ATM network.